Re: Debian stock kernel config -- CONFIG_NR_CPUS=32?

[Ron Johnson <ron.l.johnson@cox.net>]

On 10/22/2010 10:34 AM, owens@netptc.net wrote:
> > ---- Original Message ----
> > From: ron.l.johnson@cox.net
> > To: debian-user@lists.debian.org
> > Subject: Re: Debian stock kernel config -- CONFIG_NR_CPUS=32?
> > Date: Fri, 22 Oct 2010 02:00:45 -0500
> >
> > > Correct.  The amount of effort needed for cross-CPU communication,
> > > cache coherency and OS process coordination increases much more than
> >
> > > linearly as you add CPUs.
>
> In fact IIRC the additional overhead follows the square of the number
> of CPUs.

Maybe in brute-force implementations, but otherwise the machine 
would bog down after just a few CPUs.

Note that h/w engineers and OS designers/writers have put a lot of 
work into minimizing the overhead and maximize the parallelism of 
extra CPUs.

--
Seek truth from facts.